Receptacle and plug

ABSTRACT

A DC receptacle has, in a housing, a pair of connection sockets with which a pair of connection terminals of a plug used in a DC electrical equipment is adapted to be detachably electrically connected. The DC receptacle includes a circuit opening/closing unit configured to open or close a power line; and a connection verification unit for verifying the connection of the plug to the receptacle. The circuit opening/closing unit opens or closes the power line depending on the connection state between the plug and the receptacle detected by the connection verification unit.

This application is a Continuation Application of PCT InternationalApplication No. PCT/IB2011/002168 filed on Sep. 20, 2011, whichdesignated the United States.

FIELD OF THE INVENTION

The present invention relates to a DC (direct current) receptacle and aplug for DC wiring.

BACKGROUND OF THE INVENTION

Recently, solar cells and fuel cells have been widely spread. Thecurrent generated in the solar cells is DC. The DC is converted into AC,using a converter, to be used at home or provided for sale. Sinceelectric appliances generally operate with DC using an AC-DC converterfor converting AC into DC, the generated current is converted from DC toAC using a converter, and the AC is then converted into DC using theAC-DC converter. In this case, almost about 20% of the originallygenerated power is not used but lost depending on the conversionefficiency.

For this reason, recently, DC power generated by a photovoltaic powergeneration facility is stored in a storage battery such as a lithium-ionbattery, and current is supplied from the storage battery to a DCreceptacle installed in a house or the like. In addition, there has beenintroduced a DC connection device, which is used by connecting a plug ofa DC device, such as an illuminator or an electrical appliance thatoperates by receiving the supplied DC power, to the DC receptacle.

Meanwhile, there has been disclosed a DC connection device in which thetimings at which a pair of connection terminals of a plug isdisconnected from respective connection sockets of a receptacle are madedifferent from each other, thereby preventing an arc from beinggenerated at the connection terminals of the plug (see, e.g., JapanesePatent Application Publication No. 2009-146777). Also, there has beendisclosed a DC receptacle which can supply constant DC voltage to a DCdevice (see, e.g., Japanese Patent Application Publication No.2009-146827).

However, if the receptacle and plug in the conventional DC connectiondevice has the same structure as a conventional AC receptacle and ACplug, the plug may be disconnected from the receptacle even whilecurrent flows therethrough. In this case, an arc may be generatedbetween the connection terminals of the plug and the connection socketsof the receptacle, which is problematic. Particularly, unlike AC, DC hasa constant value with no zero-cross point of current and voltage.Therefore, if an arc is generated, it is difficult for the arc todisappear, and the arc is very dangerous.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a receptacle and aplug for DC wiring, in which can have further improved safety by surelypreventing the generation of an arc when the plug using DC is insertedinto or removed from the receptacle.

In accordance with an aspect of the invention, there is provided a DCreceptacle having, in a housing, a pair of connection sockets with whicha pair of connection terminals of a plug used in a DC electricalequipment is adapted to be detachably electrically connected, thereceptacle including: a circuit opening/closing unit configured to openor close a power line electrically connected to the connection sockets;and a connection verification unit configured to verify the connectionof the plug to the receptacle, wherein the circuit opening/closing unitopens or closes the power line depending on the connection state betweenthe plug and the receptacle detected by the connection verificationunit.

Preferably, the circuit opening/closing unit has a relay, wherein theconnection verification unit has a conductive contact adapted to becontacted with a conductive terminal of the plug, and wherein the relayis configured to close the power line when the contact and the terminalare in a contact state and open the power line when the contact and theterminal are in a non-contact state.

Preferably, the DC receptacle further includes a current measurementunit for measuring a current value of current flowing through the powerline; a locking mechanism unit for fixing the plug to the receptacle;and a control unit for controlling the operation of the circuitopening/closing unit depending on the connection state between thecontact and the terminal and for controlling the locking mechanism unitso that the plug is not removed from the receptacle when the currentvalue is measured by the current measurement unit.

Preferably, the connection verification unit is a movable piece whichmoves in a predetermined direction in response to the movement of alocking mechanism unit of the plug for fixing the plug to thereceptacle, and wherein the circuit opening/closing unit is configuredto close the power line by the movement of the movable piece to apredetermined position when the locking mechanism unit is in a lockstate and open the power line by the return of the movable piece fromthe predetermined position when the locking mechanism unit is in arelease state.

Preferably, the circuit opening/closing unit is a breaker providedoutside the housing of the receptacle, wherein the connectionverification unit transmits information on connection between thereceptacle and the plug to the breaker through a signal line, andwherein the breaker opens or closes the power line based on thecorresponding connection information.

Preferably, the DC receptacle further includes a current measurementunit for measuring a current value of current flowing through the powerline; a display unit for displaying a conducting state of the powerline; and a control unit for controlling the display unit to display theconducting state when the current value is measured by the currentmeasurement unit.

Preferably, the DC receptacle further includes a display unit fordisplaying a conducting state of the power line, wherein the controlunit controls the display unit to display the conducting state when thecurrent value is measured by the current measurement unit.

Preferably, the display unit is a light emitting diode or a liquidcrystal display unit.

In accordance with another aspect of the invention, there is provided Aplug which is adapted to be used corresponding to the DC receptacle.

In the receptacle and the plug for DC wiring in accordance with thepresent invention, the circuit opening/closing unit opens or closes thepower line depending on a connection state between the plug and thereceptacle, which is detected by the connection verification unitprovided in the receptacle. For this reason, it is possible to furtherimprove safety by surely preventing the generation of an arc when theplug using DC is inserted into or removed from the receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become apparentfrom the following description of preferred embodiments, given inconjunction with the accompanying drawings, in which:

FIGS. 1A and 1B are schematic sectional views of a receptacle and a plugfor DC wiring in accordance with a first embodiment of the presentinvention;

FIG. 2 is a schematic sectional view of a receptacle and a plug for DCwiring in accordance with a second embodiment of the present invention;

FIG. 3A is a schematic perspective view of a receptacle and a plug forDC wiring in accordance with a third embodiment of the presentinvention, and FIG. 3B is a schematic sectional view of the receptacleand the plug for DC wiring;

FIGS. 4A to 4C are schematic sectional views illustrating the operationof a receptacle and a plug for DC wiring in accordance with a fourthembodiment of the present invention; and

FIG. 5A is a schematic sectional view of a receptacle and a plug for DCwiring in accordance with a fifth embodiment of the present invention,FIG. 5B is another schematic sectional view of the receptacle and theplug for DC wiring, and FIG. 5C is a perspective of the receptacle andthe plug for DC wiring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings which form a part hereof. In thedrawings, the same reference numerals are used for the same or likeparts and redundant description thereof will be omitted.

First Embodiment

A receptacle 3 and a plug 2 for DC wiring in accordance with a firstembodiment are shown in FIG. 1. The plug 2 includes a pair of connectionterminals 21 used in electrical equipment which operates with DC, and isused for DC distribution. In addition, the plug 2 further includes aterminal 22 for connection verification, which has conductivity of ametal member or the like and is used to verify the connection betweenthe plug 2 and the receptacle 3. The plug 2 is also used as a plug of anelectric appliance such as an illuminator, PC or liquid crystaltelevision, in which DC is used.

The receptacle 3 is installed indoors, for example, on a wall or a floorand allows the plug 2 to be removably inserted into the receptacle 3.The receptacle 3 has, in a housing thereof, a pair of connection sockets30 for DC feeding, and the connection terminals 21 of the plug 2 areelectrically connected to the connection sockets 30. The receptacle 3 isprovided with a connection verification unit for verifying theconnection of the terminal 22 of the plug 2 to the receptacle 3 usingtwo contacts A and B, a switch 33 connected in series to a power line32, a coil 34 a which allows the switch 33 to be in a closed state (ON)when current flows in the coil 34 a and which allows the switch 33 to bein an open state (OFF) when no current flows in the coil 34 a, and arelay power supply 34 for supplying power to the coil 34 a. Here, theswitch 33 and the coil 34 a constitute a relay 45 serving as a circuitopening/closing unit.

The connection verification unit 31 has the two contacts A and B forcontacting the terminal 22. If the terminal 22 of the plug 2 is insertedinto the receptacle 3, current flows through an electric circuitincluding the connection verification 31, the relay power supply 34 andthe coil 34 a. While the plug 2 is not inserted into the receptacle 3,the switch 33 is in the open state (OFF). While the plug 2 is insertedinto the receptacle 3, the switch 33 is in the closed state (ON) bymeans of electromagnetic operation of the coil 34 a.

Next, the operation of the receptacle 3 and the plug 2 for DC wiring inaccordance with the first embodiment will be described. If the plug 2 isinserted into the receptacle 3, the connection terminals 21 areconnected to the connection sockets 30, and the terminal 22 of the plug2 is then connected to the contacts A and B. The current from the relaypower supply 34 flows in the coil 34 a, so that the switch 33 becomes inthe closed state (ON) to start applying current to the plug 2.Meanwhile, when the plug 2 is removed from the receptacle 3, the contactB of the connection verification unit 31 is separated from the terminal22 and the switch 33 immediately becomes in the open state (OFF) beforethe connection terminals 21 are separated from the connection sockets30, and then, the connection terminals 21 are separated from theconnection sockets 30.

As described above, in the receptacle 3 and the plug 2 for DC wiring inaccordance with the first embodiment, the verification of a connectionstate in the connection verification unit 31 is interlinked with theon/off operation of the switch 33. Thus, when the plug 2 is notinserted, there is no voltage difference between the connection sockets30 of the receptacle 3. In addition, even when the plug 2 isunintentionally removed, the switch 33 is turned off simultaneously withthe start of the removal of the plug 2 before the connection terminals21 are separated from the connection sockets 30. Thus, it is possible tosurely prevent an arc from being generated between the connectionterminals 21 of the plug 2 and the connection sockets 30 of thereceptacle 3, which improves safety.

Second Embodiment

Unlike the configuration of the first embodiment, in a receptacle 3 anda plug 2 for DC wiring in accordance with a second embodiment, thereceptacle 3 includes a measurement unit 35, a control unit 36 and alocking mechanism unit 37 as shown in FIG. 2. The measurement unit 35includes an ammeter or the like, which is connected in series to thepower line 32 and transmits a detected current value to the control unit36. The control unit 36 has a CPU and controls a switch of the relay 45to be turned on when the connection between the plug 2 and thereceptacle 3 is verified by the connection verification unit 31. Thecontrol unit 36 operates the locking mechanism unit 37 to make the plug2 not be removed from the receptacle 3 while the current value isdetected by the measurement unit 35. The locking mechanism unit 37 isconnected to the control unit 36 and is automatically operated to fix orrelease the plug 2 based on a predetermined signal from the control unit36.

Next, the operation of the receptacle 3 and the plug 2 for DC wiring inaccordance with the second embodiment will be described. When the plug 2is inserted, the control unit detects the connection between the plug 2and the receptacle 3 through the contact between a contact C of theconnection verification unit 31 and the terminal 22 of the plug 2, andturns on the switch of the relay 45 that is an opening/closing mechanismunit. Furthermore, if the current value is detected by the measurementunit 35, the control unit 36 operates and controls a removal preventionmechanism of the locking mechanism unit 37 to allow the plug 2 not to beremoved from the receptacle 3.

Meanwhile, when the current is not measured by the measurement unit 35,the control unit 36 releases the locking mechanism unit 37 to allow theplug 2 to be removed. In the state in which the plug 2 is removed fromthe receptacle 3, the contact C of the connection verification unit 31is separated from the terminal 22. Therefore, the control unit 36detects the separation between the plug 2 and the receptacle 3 and turnsoff the switch of the relay 45.

As described above, in the receptacle 3 and the plug 2 for DC wiring inaccordance with the second embodiment, the contact C of the connectionverification unit 31 contacts the terminal 22 of the plug 2, and acurrent is then measured by the measurement unit 35. If the current isdetected by the measurement unit 35, the control unit 36 operates thelocking mechanism unit 37 to allow the plug 2 not to be removed from thereceptacle 3. For this reason, it is possible to prevent the plug 2 frombeing unintentionally removed from the receptacle 3 while current flowsthrough the plug 2, which prevents the generation of an arc and improvesafety.

The operation of the second embodiment is similar to that of the firstembodiment. When the plug 2 is inserted into the receptacle 3, theterminal 22 of the plug 2 is preferably contacted with the contact C ofthe connection verification unit 31 after the connection terminals 21are connected to the connection sockets 30. When the plug 2 is removedfrom the receptacle 3, the contact C of the connection verification unit31 is preferably separated from the terminal 22 before the connectionterminals 21 are separated from the connection sockets 30.

Third Embodiment

In a receptacle 3 and a plug 2 for DC wiring in accordance with a thirdembodiment, as shown in FIGS. 3A and 3B, the connection sockets 30 ofthe receptacle 3 is connected to a remote control breaker 4 that is abreaker for wiring through the power line 32. The connectionverification unit 31 has a function of transmitting a bit signal or thelike, which represents a connection state between the plug 2 and thereceptacle 3, to the remote control breaker 4 through a signal line 5.The connection verification unit 31 is a mechanical button and mayverify the connection state between the plug 2 and the receptacle 3based on the conducting state thereof.

Next, the operation of the receptacle 3 and the plug 2 for DC wiring inaccordance with the third embodiment will be described. When the plug 2is inserted into the receptacle 3, the connection verification unit 31transmits the information on connection between the plug 2 and thereceptacle 3 to the remote control breaker 4 through the signal line 5.Then, if the remote control breaker 4 receives the connectioninformation indicating the connection between the plug 2 and thereceptacle 3, the remote control breaker 4 closes the power line 32 (inthe closed state). Meanwhile, when the plug 2 is removed from thereceptacle 3, the connection verification unit 31 transmits theconnection information corresponding to the disconnection between theplug 2 and the receptacle 3 to the remote control breaker 4, and theremote control breaker 4 receiving the corresponding information opensthe power line (in the open state). That is, the remote control breakerprovided in the third embodiment serves as a circuit opening/closingunit.

As described above, in the receptacle 3 and the plug 2 for DC wiring inaccordance with the third embodiment, the remote control breaker 4 is inthe disconnection between the plug 2 and the receptacle 3 when theconnection of the plug 2 to the receptacle 3 is not verified by theconnection verification unit 31. For this reason, no voltage isgenerated between the connection sockets 30 of the receptacle 3 toimprove safety, and it is possible to prevent the generation of an arc.

Further, the remote control breaker 4 that is a circuit opening/closingmechanism is provided outside the housing of the receptacle 3, and thusthe configuration of the receptacle 3 can be simplified.

The operation of the third embodiment is similar to that of the firstembodiment. When the plug 2 is inserted into the receptacle 3, theconnection verification unit 31 is preferably configured to verify thatthe plug 2 is inserted into the receptacle 3 after the connectionterminals 21 have been connected to the connection sockets 30. Then, theconnection verification unit 31 transmits the connection information tothe remote control breaker 4. When the plug 2 is removed from thereceptacle 3, the connection verification unit 31 is preferablyconfigured to verify that the plug 2 has been removed from thereceptacle 3 before the connection terminals 21 are separated from theconnection sockets 30. Then, the connection verification unit 31transmits the connection information to the remote control breaker 4.

Fourth Embodiment

In a receptacle 3 and a plug 2 for DC wiring in accordance with a fourthembodiment, as shown in FIGS. 4A to 4C, the plug 2 is provided with alocking mechanism unit 23 that is a removal prevention mechanism. Thereceptacle 3 is provided with a movable piece 38 serving as a connectionverification unit, and a pair of opening/closing members 39 formechanically opening or closing the power line 32 in response to themovement of the movable piece 38 depending on the lock operation of thelocking mechanism unit 23. That is, the opening/closing members 39provided in the fourth embodiment serve as a circuit opening/closingunit.

The operation of the receptacle 3 and the plug 2 for DC wiring inaccordance with the fourth embodiment will be described. The movablepiece 38 does not operate in the state before the plug 2 is insertedinto the receptacle 3 as shown in FIG. 4A and in the state in which theplug 2 is just inserted into the receptacle 3 as shown in FIG. 4B. Thus,since contacts 39 a of the pair of opening/closing members 39 areseparated from each other, no current flows through the power line 32.In addition, if the locking mechanism unit 23 of the plug 2 performslocking operation as shown in FIG. 4C, i.e., if the locking mechanismunit 23 is moved in the direction from the plug 2 to the receptacle inthe state where the plug 2 is inserted in the receptacle 3, the movablepiece 38 moves downward in FIGS. 4A to 4C. Accordingly, the movablepiece 38 pushes one end portions of the opening/closing members 39, sothat the contacts 39 a contact each other and the power line 23 is in aconducting state. In the conducting state, the plug 2 is fixed by thelocking mechanism unit 23 so as not to be removed from the receptacle 3.

Meanwhile, in a case when the plug 2 is removed from the receptacle 3,the locking mechanism unit 23 is released. That is, if the lockingmechanism unit 23 is moved in the direction from the receptacle 3 to theplug 2 in the state in which the plug 2 is inserted in the receptacle 3,the movable piece 38 moves upward in FIGS. 4A to 4C. Accordingly, thestate in which the movable piece 38 pushes the one end portions of theopening/closing members 39 is released, and the contacts 39 a of theopening/closing members 39 are separated from each other, so that nocurrent flows through the power line 32.

In accordance with the configuration described above, in the receptacle3 and the plug 2 for DC wiring in accordance with the fourth embodiment,the contacts 39 a of the opening/closing members 39 are always in thecontact state, in the lock state of the locking mechanism unit 23, inwhich the plug 2 cannot be freely removed from the receptacle 3.Furthermore, in the release state of the locking mechanism unit 23, thecontacts 39 a of the opening/closing members 39 are always in theseparation state, in which the plug 2 can be freely removed from thereceptacle 3. For this reason, it is possible to prevent the plug 2 frombeing unintentionally removed from the receptacle 3 in the conductingstate and to prevent an arc from being generated even when the plug 2 isremoved from the receptacle 3, thereby improving safety.

Fifth Embodiment

In a receptacle 3 and a plug 2 for DC wiring in accordance with a fifthembodiment, as shown in FIG. 5A, the receptacle 3 is provided with ameasurement unit 35 for measuring a current value of current flowingtherethrough, and a control unit 40 for displaying the conducting stateof the receptacle 3 on an display unit 41 when the current value isdetected from the measurement unit 35. As shown in FIG. 5B, the plug 2is provided with a measurement unit 24 for measuring a current value ofcurrent flowing therethrough, and a control unit 25 for displaying theconducting state of the plug 2 on a display unit 26 when the currentvalue is detected from the measurement unit 24. As shown in FIG. 5C, thedisplay unit 26 or 41 may be, for example, a light emitting diode (LED)or a liquid crystal display unit. The LED may emits red light in theconducting state and emits green light or turns off the light in thenon-conducting state. The liquid crystal display unit may display acurrent value.

The control unit 40 or 25 and the display unit 41 or 26 may be providedin either one of the receptacle 3 or the plug 2.

In accordance with the configuration described above, in the receptacle3 and the plug 2 for DC wiring in accordance with the fifth embodiment,the conducting state may be displayed on at least one of the displayunit 26 of the plug 2 and the display unit 41 of the receptacle 3. Thismakes users pay attention not to remove the plug 2 in the conductingstate, thereby improving safety.

The fifth embodiment may be used in combination with the first to fourthembodiments. Furthermore, in a case where the embodiment shown in FIG.5A is combined with the second embodiment, the function of the controlunit 40 shown in FIG. 5A may be added to the control unit 36 provided inthe second embodiment.

While the invention has been shown and described with respect to theembodiments, the present invention is not limited thereto. It will beunderstood by those skilled in the art that various changes andmodifications may be made without departing from the scope of theinvention as defined in the following claims.

What is claimed is:
 1. A DC receptacle having, in a housing, a pair ofconnection sockets with which a pair of connection terminals of a plugused in a DC electrical equipment is adapted to be detachablyelectrically connected, the receptacle comprising: a circuitopening/closing unit configured to open or close a power lineelectrically connected to the connection sockets; and a connectionverification unit configured to verify the connection of the plug to thereceptacle, wherein the circuit opening/closing unit opens or closes thepower line depending on the connection state between the plug and thereceptacle detected by the connection verification unit.
 2. The DCreceptacle of claim 1, wherein the circuit opening/closing unit has arelay, wherein the connection verification unit has a conductive contactadapted to be contacted with a conductive terminal of the plug, andwherein the relay is configured to close the power line when the contactand the terminal are in a contact state and open the power line when thecontact and the terminal are in a non-contact state.
 3. The DCreceptacle of claim 2, further comprising: a current measurement unitfor measuring a current value of current flowing through the power line;a locking mechanism unit for fixing the plug to the receptacle; and acontrol unit for controlling the operation of the circuitopening/closing unit depending on the connection state between thecontact and the terminal and for controlling the locking mechanism unitso that the plug is not removed from the receptacle when the currentvalue is measured by the current measurement unit.
 4. The DC receptacleof claim 1, wherein the connection verification unit is a movable piecewhich moves in a predetermined direction in response to the movement ofa locking mechanism unit of the plug for fixing the plug to thereceptacle, and wherein the circuit opening/closing unit is configuredto close the power line by the movement of the movable piece to apredetermined position when the locking mechanism unit is in a lockstate and open the power line by the return of the movable piece fromthe predetermined position when the locking mechanism unit is in arelease state.
 5. The DC receptacle of claim 1, wherein the circuitopening/closing unit is a breaker provided outside the housing of thereceptacle, wherein the connection verification unit transmitsinformation on connection between the receptacle and the plug to thebreaker through a signal line, and wherein the breaker opens or closesthe power line based on the corresponding connection information.
 6. TheDC receptacle of claim 1, further comprising: a current measurement unitfor measuring a current value of current flowing through the power line;a display unit for displaying a conducting state of the power line; anda control unit for controlling the display unit to display theconducting state when the current value is measured by the currentmeasurement unit.
 7. The DC receptacle of claim 2, further comprising: acurrent measurement unit for measuring a current value of currentflowing through the power line; a display unit for displaying aconducting state of the power line; and a control unit for controllingthe display unit to display the conducting state when the current valueis measured by the current measurement unit.
 8. The DC receptacle ofclaim 4, further comprising: a current measurement unit for measuring acurrent value of current flowing through the power line; a display unitfor displaying a conducting state of the power line; and a control unitfor controlling the display unit to display the conducting state whenthe current value is measured by the current measurement unit.
 9. The DCreceptacle of claim 5, further comprising: a current measurement unitfor measuring a current value of current flowing through the power line;a display unit for displaying a conducting state of the power line; anda control unit for controlling the display unit to display theconducting state when the current value is measured by the currentmeasurement unit.
 10. The DC receptacle of claim 3, further comprising:a display unit for displaying a conducting state of the power line,wherein the control unit controls the display unit to display theconducting state when the current value is measured by the currentmeasurement unit.
 11. The DC receptacle of claim 6, wherein the displayunit is a light emitting diode or a liquid crystal display unit.
 12. TheDC receptacle of claim 7, wherein the display unit is a light emittingdiode or a liquid crystal display unit.
 13. The DC receptacle of claim8, wherein the display unit is a light emitting diode or a liquidcrystal display unit.
 14. The DC receptacle of claim 9, wherein thedisplay unit is a light emitting diode or a liquid crystal display unit.15. The DC receptacle of claim 10, wherein the display unit is a lightemitting diode or a liquid crystal display unit.
 16. A plug which isadapted to be used corresponding to the DC receptacle of claim
 1. 17. Aplug which is adapted to be used corresponding to the DC receptacle ofclaim
 2. 18. A plug which is adapted to be used corresponding to the DCreceptacle of claim
 3. 19. A plug which is adapted to be usedcorresponding to the DC receptacle of claim
 4. 20. A plug which isadapted to be used corresponding to the DC receptacle of claim 5.